The present invention relates to a paper quality determination sensor for determining quality of paper sheets such as banknotes as paper money which are deposited into or drawn from, for example, an automatic teller machine (ATM), and more particularly to a paper quality determination sensor for accurately detecting the quality and condition of paper sheets without being affected by the thickness thereof and a faulty banknote sorting device.
As a paper sheet of the kind described above, banknotes which are paper money, are taken as an example for explanation. Banknotes tend to be broken and become dirty while they are circulated for a long time, or banknotes tend to become soft gradually even if they are not damaged externally. In the event that supple (unrigid), deformed or broken banknotes are used in automatic teller machines or the like which are identified as improper for circulation, the banknotes may get stuck (or jammed) inside the machine.
To cope with this, there is known a paper quality determination device for determining, so to speak, indirectly whether banknotes deposited into the automatic teller machine are proper or improper for use or circulation, by optically detecting missing portions or the degree of dirtiness of banknotes so deposited or analyzing the frequency of feeding noise generated when the banknotes are deposited, or an improper or faulty banknote sorting device with such a paper quality determination device.
With an indirect detecting system as described above, however, since the system is constructed so as to detect the degree of faultiness of banknotes without contacting them, the indirect detecting system cannot specify the stiffness of banknotes in circulation which causes the jamming, and this increases the detection error and hence deteriorates the reliability of the system.
Additionally, the indirect detecting system cannot detect the deformation and breakage of paper sheets which are objects to be inspected.
To cope with this, there have been proposed a so-called direct-type determination device for directly detecting the stiffness of circulating banknotes. For example, JP-A-09-040216, JP-A-10-111968 and JP-A-10-213581 are known.
One example of the direct-type detecting devices as disclosed in those publications will be described with reference to FIGS. 8 and 9.
This prior art device comprises a pick-up roller 94 for initial feeding provided so as to confront the feeding surface of a banknote 93 that is to be fed from a stacker 92, a feed roller 95, a gate roller 96 and a feed detecting sensor 97, the feed roller 95, the gate roller 96 and the feed detecting sensor 97 being disposed at a feeding portion of the device, and thereby operates for feeding banknotes 93 contained in the stacker 92.
In this construction, the tilting condition of a tilting lever 98 which is integral with the gate roller 96 and adapted to variably tilt in response to the stiffness of the fed banknotes 93 so as to allow the passage thereof to be detected with a strain gauge detection sensor 99 to thereby determine the stiffness of the banknotes 93 so fed, whereby they are determined as proper or faulty for circulation.
With the direct-type detecting device described above, however, since the construction is such that the strain gauge detection sensor is combined with the gate roller which is regulated with respect to the rotation thereof, the rush-in resistance and feed resistance of banknotes are increased, and detection values of the device are largely changed by the thickness of banknotes, this causing a problem that with banknotes of a specific country which are supple for the thickness thereof, it is difficult to determine whether banknotes are proper or improper.
The present invention was made in view of these situations, and an object thereof is to realize by paying attention to the paper quality reaction force inherent in paper sheets, a paper quality determination sensor for accurately detecting the stiffness (rigidity) of papersheets and further the thickness and deformation and breakage thereof without being affected by the thickness and/or deformation of paper sheets, and a faulty banknotes sorting device/paper quality measuring device.
The present invention is provided with a biasing means for applying a biasing force to a paper sheet which is an object to be detected so as to detect a reaction force that the paper sheet generates when resisting against the biasing means.
The biasing means is, for example, a sensor lever for supporting a sensor roller, and it is designed so that a biasing force is applied to a paper sheet by virtue of the elasticity inherent in the sensor lever itself. A reaction force generated from a paper sheet can be measured by providing on the sensor lever a detection sensor for detecting the traveling amount of the sensor lever. The condition of paper sheets can easily be determined from the magnitude of the reaction force, a change therein with time, and the amplitude thereof, or the like.